All steps for the project works, I created the printString, readString, readSector, and handleInterrupt21 functions.
To verify that printString (step 1) solely works, uncomment line 12 in the main and comment out the rest in main besides the while loop.
To verify that readString+printString (step 2) works, uncomment lines 15,16, and 17 in the main and comment out the rest in main
besides the while loop.
To verify that readSector (step 3) solely works, uncomment line 18 and comment out the rest besides the while loop in main.
To verify that interrupt21 (step 4 and 5) work, keep the code as is.